1. Field of the Invention
The present invention relates to an SOx gas sensor and a method of measuring concentration of SOx gas.
2. Description of the Related Art
Conventionally, an SOx gas sensor using a solid electrolyte material has been studied.
For example, Patent Document 1 discloses a gas sensor for detecting SOx gas in which a sub electrode of sulfate is provided on a base material composed of a solid electrolyte material. The gas sensor has a structure in which a mixed body of sulfate including silver sulfate is used as the sulfate of the sub electrode, a metal electrode including silver is provided on a surface of the sub electrode, and a platinum film is provided to cover a surface of the metal electrode.
However, it was necessary to further improve thermal stability of the gas sensor disclosed in Patent Document 1, because silver sulfate used for the sub electrode easily decomposes, as a result, thermal decomposition gradually occurs at 600° C., which is an operating temperature of the gas sensor. Further, it was also necessary to improve chemical stability of the gas sensor disclosed in Patent Document 1. Although an SOx gas sensor is often used for measuring components in exhaust gas (flue gas), the exhaust gas includes various accompanying components which can poison silver sulfate.